An important area in cancer research is metastasis where tumor cells invade adjacent tissues and produce secondary tumors in distant parts of their host. Recent experimental evidence suggests that these characteristics are determined by cell surface properties. In a murine model system utilizing variant B16 melanoma cell lines, it was demonstrated that cell lines with higher metastatic potential (defined by the formation of more metastases per input i.v. or s.c. tumor cell) could be derived by a regimen of passing tumors from secondary sites into tissue culture, then reimplanting i.v., and repeating the process several times. Each successive line produced significantly more lung tumors than the parent line. We propose to use these cells grown in vivo as ascites tumors or in vitro in tissue culture to determine the cell surface characteristics responsible for their metastatic properties. Chemical, enzymatic and ultrastructural techniques will be utilized to study cells grown in vitro and in animals. Surface degradative enzymatic activities (proteases and glycosidases) will be investigated with newly developed radioisotope assays. Cell adhesive characteristics will be examined by quantitative cell aggregation using a particle counting assay and attachment of radiolabeled cells to cell monolayers. Cell surface antigens will be identified using cytotoxic and quantitative absorption assays, and surface saccharides will be identified by plant lectin agglutination and quantitative labeling. Ultrastructural localization of specific antigens and saccharides will be determined using ferritin-conjugated antibodies and lectins, and certain cell surface constituents will be assayed by chemical procedures. The information gathered will be utilized to modify experimental metastasis by chemical or enzymatic means with the goal of reducing secondary tumor formation.